NB-IoT Module Series
BC95 Hardware Design
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3.8.3. UART Application
A reference design of 3.3V level match is shown as below.
Peripheral
TXD
RXD
1K
TXD
RXD
RI
EINT
Module
Voltage level: 3.3V
1K
1K
GND
GND
TXD
RXD
GND
Test points
RESET
VBAT
VBAT
RESET
Figure 11: Level Match Design for 3.3V System
1. In order to reduce the power consumption of the system, it is highly recommended to add a resistor
with resistance greater than 1KΩ on the UART port signal traces when the host’s voltage level is 3V or
3.3V.
2. For systems with a higher voltage level, a level shifter IC could be used between the host and the
module.
3. It is recommended to reserve the test points (RXD, TXD, RESET and VBAT) for firmware upgrading.
The following circuit shows a reference design for the communication between module and PC. As the
electrical level of module is 3.0V, a RS-232 level shifter must be used. Please make sure the I/O voltage
of level shifter which connects to module is 3.0V.
NOTE
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